NEW DELHI (AP) -- Two Indian navy sailors are missing and seven others have been hospitalized after they were overcome by smoke during a firefighting training exercise on board a diesel-powered submarine off Mumbai's coast.

A navy spokesman, Capt. D.K. Sharma, says a naval helicopter took the seven sailors to a navy hospital in Mumbai, but that two others are unaccounted for.

He says an inquiry has been ordered into Wednesday's incident.

Sharma says the Russian-made submarine did not suffer any damage.

Last August, another of the navy's Russian-made diesel-powered submarines, the INS Sindhurakshak, caught fire after an explosion and sank at its home port in Mumbai, killing all 18 sailors on board.